New findings by international research group of scientists from England, China and Denmark just published suggest that sea level will likely be 30-70 centimetres higher by 2100 than at the start of the century even if all but the most aggressive geo-engineering schemes are undertaken to mitigate the effects of global warming and greenhouse gas emissions are stringently controlled.

"Rising sea levels caused by global warming are likely to affect around 150 million people living in low-lying coastal areas, including some of the world's largest cities," explained Dr Svetlana Jevrejeva of the National Oceanography Centre.

Most scientists agree that anthropogenic carbon dioxide emissions contribute greatly to global warming, and that these emissions need to be controlled if damaging future impacts such as sea-level rise are to be averted. But if we fail to do so, is there a 'Plan B'?

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Scientists have proposed ways of 'geo-engineering' the Earth system to tackle global warming, thereby reducing its impact on both the main contributors of sea level rise: thermal expansion of ocean water and melting of glaciers and ice sheets. Jevrejeva and her colleagues have modelled sea level over the 21st century under various geo-engineering schemes and carbon dioxide emission scenarios.

"We used 300 years of tide gauge measurements to reconstruct how sea level responded historically to changes in the amount of heat reaching the Earth from the Sun, the cooling effects of volcanic eruptions, and past human activities," said Jevrejeva. "We then used this information to simulate sea level under geo-engineering schemes over the next 100 years."